Haloalkyl phosphinic acids and their application to cotton

ABSTRACT

BIS(CHLOROMETHYL)PHOSPHINIC ACID IS PREPARED BY A NEW METHOD; OTHER PHOSPHINIC ACIDS ARE PREPARED BY REACTING CERTAIN KETONES WITH HYPOPHOSPHORUS ACID; AND NEW CELLULOSIC DERIVATIVES ARE PREPARED BY CROSSLINKING FIBROUS CELLULOSE WITH THESE PHOSPHORUS CONTAINING COMPOUNDS.

United States Patent G 3,636,088 HALOALKYL PHOSPHINIC ACIDS AND THEIR APPLICATION TO COTTDN Leon H. Chance and Ethel K. Leonard, New Orleans, and George L. Drake, Jr., Metairie, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Application Jan. 24, 1969, Ser. No. 823,206, which is a division of application Ser. No. 635,680, May 3, 1967, now Patent No. 3,484,184. Divided and this application Nov. 14, 1969, Ser. No. 871,295

Int. Cl. C07s 9/30 US. Cl. 260502.4 R 1 Claim ABSTRACT OF THE DISCLOSURE Bis(chloromethyl)phosphinic acid is prepared by a new method; other phosphinic acids are prepared by reacting certain ketones with hypophosphorus acid; and new cellulosic derivatives are prepared by crosslinking fibrous cellulose with these phosphorus containing compounds.

This application is a division of Ser. No. 823,206, filed Jan. 24, 1969, which was a division of Ser. No. 635,680, filed May 3, 1967, now US. Pat. No. 3,484,184.

A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to haloalkyll phosphinic acids, to the preparation thereof, and to a process for imparting improved physical and chemical properties to cellulosic textiles by treating said cellulosic textiles with the organophosphorus compounds of this invention. More specifically this invention relates to the preparation of a known phosphinic acid by a new method, to the preparation of two new compounds by another method, and to the utilization of these compounds in textile applications which Would yield goods with Wet wrinkle resistance, cationexchange properties, fire-retardance, and other useful properties.

The main object of the instant invention is to provide a process for imparting to cotton and other cellulosic textiles improved wet wrinkle recovery.

A second object of the instant invention is to provide a process for imparting to cotton and other cellulosic textiles cation-exchange properties.

A third object of the instant invention is to provide a process for improving the comfort factor of garments made from cotton and other cellulosic textiles by providing the treated textile with increased moisture regain.

A fourth object of the instant invention is to provide textiles with reduced combustibility as an additional physical factor obtained in the finished goods together with the imparted comfort factor.

A fifth object of the instant invention is to provide new methods of preparing phosphorus-containing compounds which also contain active halogen groups.

A sixth object of the instant invention is to provide a new method of preparing known and useful compounds.

A seventh object of the instant invention is to disclose the new phosphinic acid type compounds produced by processes of the instant invention.

Searching the prior art we find that acetone reacts with hypophosphorus acid to produce bis(l-hydroxyisopropyl) phosphinic acid (Bellatein I, 652 (1918)). The reaction requires several days of refluxing, and rather low yields are obtained. K. M. Moedritzer (J. Amer. Chem. Soc. 85, 4381-4 (1961)) prepared bis(chloromethyl)phosphinic chloride by a complex four step reaction. G. L. Drake, Jr.

et al. (US. Pat. 2,979,374) reacted chloromethyl phosphonic acid with fibrous cellulose in the presence of alkali to produce phosphonomethylated cellulosic materials having reduced combustibility and cation-exchange properties. Cotton fabrics treated with chloromethyl phosphonic acid, however, do not have improved wrinkle resistance and do have a slick feel when wet with water.

One improvement which is a facet of the present invention over the prior art is this. We have found that when halogen substituted acetonessuch as chloroacetone and dichloroacetoneare used the reaction proceeds rapidly and with good yields. We have attributed this to the activating influence of the halogens on the carbonyl groups of the acetone. In reference to the complex, four step reaction of Moedritzer we differ in that we prepare the bis (chloromethyl)phosphinic acid by a simple new process with good yields wherein bis(hydroxymethyl)phosphinic acid is reacted with thionyl chloride, and the resulting phosphinic chloride is then hydrolyzed with water.

In the course of investigation we have found that phosphinic acids having the graphic formula where X represents either hydrogen or a halogen, and Y represents a halogen, can be prepared by reacting hypophosphorus acid with haloacetones having the graphic formula CHgX- -CHzY where X and Y are members of the group halogen and hydrogen, with the proviso that when one is hydrogen the other must be halogen.

We have also found that phosphinic acids of the graphic formula 6 HOP(CHX)2 where X represents a halogen, can be prepared by reacting bis(hydroxymethyl)phosphinic acid with a suitable halogenating agent such as SOX PX or PX where X represents a halogen atom, followed by hydrolysis of the resulting phosphinic halide.

We have further found that the sodium salt of the compound (bis(iodomethyl)phosphinic acid can also be prepared by reacting bis(chloromethyl)phosphinic acid with sodium iodide in a suitable solvent.

In accordance with the present invention the reaction of hypophosphorus acid with the haloacetones is carried out by heating crystalline hypophosphorus acid with an excess of the haloacetone Without the use of a solvent. Although organic solvents, such as methanol, ethanol, or isobutanol, may be used in the reaction the preferred procedure is to carry out the reaction without a solvent because higher yields are obtained in this manner; and his (chloromethyl)phosphinic acid is prepared by reacting crystalline bis(hydroxymethyl)phosphinic acid With an excess of thionyl chloride without the use of a solvent.

The reaction with cellulosic material takes place between the cellulosic hydroxyl groups and the halogen atoms of the alkali metal salts of the haloalkyl phosphinic acids, thereby crosslinking the cellulose through stable ether linkages. Cellulose crosslinks are shown by insolubility of the cellulose in aqueous 0.5 molar cupriethylenediarnine hydroxide. The resulting alkali metal cellulose phosphinate can be converted to the corresponding phosphinic acid by soaking the cellulose phosphinate in a dilute solution of a strong mineral acid until all of the alkali metal atoms have been replaced by hydrogen atoms. These hydrogen atoms can be replaced by other cations by immersing in 3 the appropriate solution containing the desired cation. When the cation is ammonium ion the cellulosic material has a greater reduction in combustibility than any other cation.

Cotton fibers, regenerated cotton fibers, paper, or other cellulosic materials are suitable for this invention. Cotton fiber is the preferred material, and may be in the form of fibers, sliver, yarn, or fabric, but yarn or fabric is preferred.

The reaction with cellulosic material can be carried out by using the metal salt of chloroalkyl phosphinic acids. However, the invention is not limited to the chloro deriva tives. Other halogen derivatives can be used.

The aqueous solutions suitable for use in the invention can be aqueous solutions of the haloalkylphosphinic acid and any metal hydroxide or alkali metal carbonate containing about from 2% to 20% by weight of unreacted alkali metal hydroxide or carbonate and about from 5% to 25% by weight of the haloalkylphosphinic acids. Preferred concentrations of alkali metal hydroxide or carbonate and phosphinic acid depends on the phosphinic acid being used and on the degree of cellulosic crosslinking desired. It is preferable to use the solutions while they are fresh, because the longer the solutions stand, the less eificient the reaction becomes.

The reaction of the chloroalkyl phosphinic acids with cellulosic materials may be carried out by impregnating the cellulosic material with an aqueous alkali metal hydroxide or carbonate, in excess of that required to neutralize the acid, drying, and then impregnating the dried cellulose material with an aqueous solution of the phosphinic acid, and finally curing the cellulosic material at temperatures ranging about from 110 C. to 175 C., for periods of time ranging about from 5 minutes to 30 minutes. The preferred method of carrying out the reaction involves impregnating the textile in only one aqueous solution. The chloroalkyl phosphinic acid is dissolved in aqueous alkali metal hydroxide or carbonate in excess of that required to neutralize the acid. Sodium hydroxide and sodium carbonate are preferred. The cellulosic material is impregnated with the solution, dried, and cured at temperatures ranging about from 110 C. to 175 C. for periods of time about from 5 minutes to 30 minutes, the longer times being used with the lower temperatures. When alkali metal hydroxides are used the preferred curing temperatures are in the range of about from 140 to 150 C. for about from 5 to minutes. When the alkali metal carbonates are used the preferred curing temperatures are in the range of about from 165 to 175 C. for periods of time of about from 5 to 10 minutes.

The fibrous cellulosic material can be impregnated and heated by any apparatus conventionally used for processing such materials.

The following examples illustrate procedures that have been used successfully in carrying out the invention and are not meant as a limitation thereof. Cotton fabrics which have been treated by process of this invention were tested by the standard methods recommended by the American Society for Testing Materials, Philadelphia, Pa., Committee D-15. Wet and dry wrinkle recovery were determined by the Monsanto Method, ASTM D1424-5 9; and moisture regain by ASTM D62959T. Fabric combustibility tests were carried out in this manner: The fabric samples were cut into strips 1 cm. x 5 cm., and each strip being tested was held with the surface vertical to the flame, and the long edge at the indicated angle from vertical, and ignited at the specific points. Observations were made to see whether or not the burning would continue along the strip and to determine the presence or absence of an afterglow. Equivalent weights were determined by standard titration procedures. All percentages and parts in the examples are by Weight.

4 PREPARATION OF PHOSPHINIC ACLDS. EXAMPLE 1 Bis(1-hydroxy 2-chloroisopropyl)phosphinic acid. Method I Crystalline hypophosphorus acid (33.0 grams, 0.5 mole) was dissolved in chloro-2-propanone (185.0 grams, 2.0 moles). The solution was heated on a water bath for 15% hours at about C. During the heating period the reaction mixture turned black and crystallized to a solid mass. The mass was slurried vigorously with 300 ml. of benzene to remove the black material, and the crystals were filtered. Additional crystals were recovered from the benzene filtrate by evaporation of the greater part of the benzene. The crystals were slurried again with 150 ml. of benzene containing 5 ml. of ethanol. The total crude yield was 72.5 grams or 57.6% based on the hypophosphorus acid. The M.P. of the crude produce was 149159 C. (corrected).

Purer crystals with an M.P. of 150-151 C. were obtained by stirring the crude crystals with a mixture of hot benzene and ethanol in a ratio of 30:1, cooling, filtering, and washing the white crystals on filter with acetonitrile. Analytically pure crystals were obtained by recrystallization from a mixture of benzene and ethanol. The crystals had an M.P. of 153.5-l54.5 C. (corn).

Elemental analysis.Calcd. for C H O Cl P (percent): C, 28.72; H, 5.19; C1, 28.25; P, 12.54; (equivalent weight, 250.95). Found (percent): C, 29.03; H, 5.57; Cl, 27.47; P, 11.57; (equivalent weight, 247.91).

The compound is soluble in water, alcohol, and acetone.

Method H Crystalline hypophosphorus acid (16.5 grams, 0.25 mole) and chloro-Z-propanone (50.0 grams, 0.54 mole) were dissolved in ml. of isobutanol. The solution was heated at 95100 C. for 16 hours. The isobutanol was removed by vacuum distillation, leaving a viscous brown residue which partially crystallized. To this brown mass was added ml. of benzene. The dark viscous material dissolved, leaving the crystals undissolved. The crystals were filtered and washed with benzene. They were white and weighed 6.5 grams. When recrystallized from a mixture of benzene and ethanol, the compound had a melting point of 153.5-154.5 C. and was identical with that obtained by Method 1.

EXAMPLE 2 Bis(lhydroxy 2,2'-dichloroisopropyl)phosphonic acid 1,3-dichloro-2-propanone (65.5 grams, 0.5 mole) and crystalline hypophosphorus acid (13.0 grams, 0.2 mole) were mixed and heated to 50 C. The crystals melted and were stirred to make a homogeneous solution. Heating at 50 C. was continued for 15% hours. During this time the reaction mixture solidified to a white crystalline mass. The mass was broken up and stirred successively with two 50 ml. portions of hot benzene to remove unreacted materials. The white crystals Weighed 56.7 grams. Additional crystals (1.6 grams) were recovered from the henzene to make a total yield of 50.3 grams or 91%. The crystals had an M.P. of 157-l59 C. (corrected) and was pure enough for use in examples cited below. Recrystallization from a benzene and ethanol mixture produced an analytical sample with a melting point of 141- 142 C. (corrected).

Elemental analysis.Calcd. for C H O Cl 'P (percent): C, 22.52; N, 5.47; Cl, 44.52; P, 9.68. Found (percent): C, 22,9.1; N, 3. '64; Cl, 43.54; P. 8.90.

Determination of the equivalent weight could not be determined 'by direct titration with 0.1 N NaOH, because the chlorine atoms were active enough to hydrolyze during the titration. Therefore, the compound was heated in an excess of standard 0.1 N NaOH for 2 /2 hours at 65-70" C. to hydrolyze all four chlorine atoms. The solution was then back titrated with standard 0.1 N HCl. The calculated equivalent weight by this method is one-fifth of the molecular weight, or 63.97. The equivalent weight found by the above method was 62.15.

The compound is soluble in water, alcohol, and acetone.

EXAMPLE 3 Bis(chloromethyl)phosphinic acid.Step 1 Thionyl chloride (416.5 grams, 3.5 mole) was placed in a 3-neck flask equipped with a stirrer and a reflux condenser topped with a drying tube to exclude moisture. Bis(hydroxymethyl)phosphinic acid (126.0 grams, 1.0 mole) was melted and added gradually to the stirred flask. The reaction was endothermic, the flask becoming cold during the additions. After the addition was complete, the reaction mixture was allowed to stand overnight. The excess thionyl chloride was removed by distillation. The crude bis(chloromethyl)phosphinic chloride was a liquid and weighed 170 grams, a 93.7 yield based on bis(hydroxyrnethyl)phosphinic acid.

Step 2 Crude bis(chloromethyl)phosphinic chloride (170.0 grams, 0.94 sole) was dissolved in 265 ml. of benzene, and added dropwise over a 30 minute period to a vigorously stirred flask containing 395 ml. of benzene and 20 grams (1.0 mole) of water. Stirring was continued for 6 hours at room temperature, and finally the mixture was refluxed for one hour. The flask was cooled in an ice water bath, and the crystals which separated were filtered and dried. The crude yield of bis(chloromethyl) phosphinic acid was 100%, but melted over a range of 75- 79 C. The crude crystals were stirred with a mixture of 240 ml. of benzene and 60 ml. of acetone, cooled in ice water, and filtered. The recovery was 73% of white crystals with an M.P. of 7780 C. Crystals melting at 80.5- 81.5 C. were obtained by repeating the purification step. Additional crystals were obtained from the combined benzene-acetone filtrate to give a total yield of pure crys- -tals of 69%. The melting point (80.5%81.5 'C., corrected) agreed with that of bis(chloromethyl)phosphinic acid prepared by a different method in the literature.

Elemental analysis.Calcd. for C H O Cl P (percent): C, 14.74; H, 3.09; Cl, 43.52; P, 19.01; (equivalent weight, 1 62.89). Found (percent): C, 14.81; H, 3.11; Cl, 43.56; P, 19.10; (equivalent weight, 160.30).

The compound was soluble in water, alcohol, and acetone.

EXAMPLE 4 Bis(iodomethyl)phosphinic acid, sodium salt Bis(chloromethyl)phosphinic acid (16.5 g.) was dissolved in aceton (75 ml.) and added to a flask containing sodium iodide (39.0 grams) in acetone (175 ml.). The mixture was refluxed with stirring for about 12 hours. The precipitated sodium chloride was filtered. The filtrate was cooled to about C. The crystals which separated were filtered and washed with cold acetone. Pale yellow crystals (5.5 grams) were obtained. The acetone filtrate was evaporated to about 30 ml. volume. Black crystals were obtained. The black color was due to the presence of free iodine. The crystals were washed with absolute ethanol (50 ml.). Pale yellow crystals (1.8 grams) were obtained. Total crude yield was 7.3 grams. Lustrous white crystals were obtained by recrystallization from water-ethanol (1 :4 volume ratio). The product was largely the sodium salt of bis(iodomethyl)phos phinic acid.

Elemental analysis.Calcd. (percent): C, 6.53; N, 1.10; I, 69.00; P, 8.42. Found (percent): C, 7.66; H, 1.26; I, 60.56; P, 965.

Application to cotton fabric In all of the following examples 80 x 80 mercerized cotton printcloth was used. The fabric was immersed in the solution and the excess squeezed out by passing through squeeze rolls to a wet pickup of -100% depending on solution concentrations. The fabric was then dried and cured without tension unless otherwise stated, and finally washed and dried.

For 'brevity, the phosphinic acids will be designated as follows: bis(l hydroxy 2 chloroisopropyl)phosphinic acid-HCPA; bis( 1 hydroxy 2,2 dichloroisopropyl) phosphinic acid-HDPA; and bis(chloromethyDphosphinic acid-HCPA.

EXAMPLE 5 HCPANaOH catalyst Solutions were prepared by dissolving HCPA in aqueous NaOH solutions of the concentrations indicated in Table I, while keeping the solution cool to prevent spontaneous heating up. All solutions contained .15 HCPA. Cotton fabric samples were treated with freshly prepared solutions, as well as with solutions aged from 2 to 24 hours to demonstrate solution stability. Fabric samples, after impregnation, were dried for 5 minutes at 85 C. and cured for 5 minutes at 140 C., washed and dried. Fabric data are shown in Table I. Very slight fabric discoloration was completely removed by a mild chlorine bleach.

TABLE I Wrinkle Phosrecovery Cation- Age of phorus, (degrees) Moisture exchange soln., content, regain, capacity hrs. percent Wet Dry percent meg/gm.

Fresh 0.06 232 Fresh 0.77 264. Fresh 0. 98 235 201 2 0.05 236 196 4 0.72 234 189 24 0.35 221 178 Fresh 0. 221 0.75 230 180 Fresh 0. 89 224 192 0.65 228 185 fabric 198 191 EXAMPLE 6 HCPA (5.25 grams) was dissolved in 29.75 grams of 15% aqueous NaOH. Fabric impregnated with this solution was cured for 5 minutes at 140 C., omitting the drying step. The fabric contained 0.89% P and had a wet wrinkle recovery of 239.

A second sample of fabric was treated similarly except it was cured for 30 minutes at C. It had a wet wrinkle recovery angle of 247, a dry wrinkle recovery angle of 173, and phosphorus content of 0.77%.

EXAMPLE 7 A two-step method was used to apply HCPA to cotton fabric. Two fabric samples were first impregnated with a 25% aqueous solution of NaOH, dried for 5 minutes at 85 C., and then impregnated with a 20% aqueous solution of HCPA. The first sample was cured for 5 minutes at C., washed and dried. The fabric contained 0.82% P. The second sample was cured for 50 minutes at 110 C., washed and dried. It contained 0.75% P.

EXAMPLE 8 HCPANa CO Catalyst A solution was prepared by dissolving 5.0 g. of HCPA in 45 g. of 15% Na CO The solution contained 10% HCPA. Three samples of cotton fabric were impregnated with the solution and each dried for .5 minutes at 85 C. The samples were then cured for 5 minutes at temperatures shown in Table II. Wrinkle recovery angles, phosphorus content, and moisture regain are given.

TABLE II Wrinkle recovery (degrees) Moisture Phosphorus regain, content,

Curing temp., Wet Dry percent percent The samples cured at 140 C. and 165 C. were soluble in cupriethylenediamine dihydroxide, indicating little or no cross-linking. The sample cured at 175 C. was partially insoluble, indicating a little crosslinking of the cellulose.

EXAMPLE 9 Solutions were prepared in the same way as in Example except HDPA was used instead of HCPA. All solutions contained 15 HDPA. Fabric discoloration was greater than when HCPA was used, and therefore required stronger bleaching conditions to remove the color. Fabric data are shown in Table III.

A two-step method was used to apply HDPA to cotton fabric in the same manner described for the first sample in Example 7. The fabric contained 0.66% P.

EXAMPLE 11 A solution was prepared by dissolving HDPA (3.25 g.) in 15 aqueous NaOH (21.75 g.). Cotton printcloth impregnated with the solution was cured for 30 minutes at 110 C. It had a wet wrinkle recovery angle of 278 C., a dry wrinkle recovery angle of 189, and a phosphorus content of 0.79%.

EXAMPLE 12.

HDPANa CO catalyst A solution was prepared in the same manner as in Example 8 except HD-PA was used instead of HCPA. Fabric samples were treated as in Example 8. Wrinkle recovery angles, phosphorus content, and moisture regain are given in Table IV.

All of the fabric samples were insoluble in aqueous 0.5 molar cupriethylenediamine hydroxide, indicating crosslinking of the cellulose.

8 EXAMPLE 15 Solutions were prepared by dissolving BCPA in aqueous NaOH solution of the concentrations indicated in Table V, keeping the solution cool to prevent heating up due to neutralization of the acid. All solutions contained 10% BCPA. Cotton fabric samples were treated with fresh solutions as well as with solutions aged for 4 hours and 24 hours. Fabric samples, after impregnation were dried for 5 minutes at C., and cured for 5 minutes at (except for one sample cured for 5 minutes at C.), washed, and dried. Fabric data are shown in Table V.

TAB LE V Wrinkle Phosrecovery Cation- N aOH Age of phorus (degrees) Moisture exchange cone. so1n., content, regain, capacity percent hrs. percent Wet Dry percent meg/gm.

Fresh 0. 60 245 195 9. 09

Fresh 0.26

Fresh 0.60

Fresh 0.78

Fresh 0.72

Fresh 0.65

Fresh 0.58

" Cured 5 minutes at 165 0.

Very slight fabric discoloration was removed by a mild chlorine bleach.

EXAMPLE 14 A solution was prepared by dissolving BCPA (2.5 grams) in 15% aqueous NaOH (22.5 grams). Cotton printcloth impregnated with the solution was cured for 30 minutes at 110 C. It had a wet Wrinkle recovery angle of 266, a dry wrinkle recovery angle of 180, and a phosphorus content of 0.55%

EXAMPLE 15 BCPA--Na CO catalyst A solution was prepared in the same manner as in Example 8 except BCPA was used instead of HCPA. Fabric samples treated in the same manner as in Example 8. Wrinkle recovery angles, phosphorus content and moisture regain of the fabric samples are given in Table VI.

amine hydroxide, were insoluble, indicating crosslinking of the cellulose.

EXAMPLE 16 Three solutions were prepared as follows: (1) HCPA (6.75 g.) was dissolved in 15 aqueous NaOH (38.25 g.); (2) HDPA (7.5 g.) was dissolved in 15 aqueous NaOH (42.5 g.); (3) BOPA (5.0 g.) was dissolved is 12.5% aqueous NaOH (45.0 g.) Cotton fabric samples were impregnated with each solution, and each sample placed on a pin frame at its original dimensions before impregnation. The fabrics were then dried 5 minutes at 85 C. and cured 5 minutes at 140 C. The pin frame maintained the fabric at constant dimensions during the drying and curing operations. The fabric was removed from the pin frame, washed, replaced on the pin frame, and dried at constant dimensions. Data for the fabric samples are shown in Table VII.

All of the samples were insoluble in aqueous 0.5 molar cupr-iethylenediamine hydroxide solution. This is an indication that the cellulose is crosslinked.

TABLE VII Wrinkle recovery Breaking Elongation Tearing Flex Phosphorus Gation- (W plus F) strength at break strength Moisture abrasion content, exchange (filling) (filling) (filling) regain, (filling) Compound percent Meg/gm. Wet Dry (lbs) percent gl'flS. percent cycles 0. 95 0. 321 236 195 33. 6 19. 1 500 10. 6 535 1. 10 O. 414 276 201 22. 6 23. 400 10. 3 250 0. 91 0. 278 272 206 25. 2 26. 1 160 10. 1 512 Control 0. 052 158 191 59. 1 25. 9 787 7. 799

EXAMPLE 17 ble in aqueous 0.5 molar cupriethylenediamine hydroxide,

TABLE VIII Phosphorus Strip burn angle, degrees Fabric content, treatment percent Na salt N H4 salt Acid form H CPA 1. 58 90 HDPA 1.10 O 90 B CPA 0. 72 0 90 90 All of the treated samples left a black charred residue with no afterglow. The control fabric burned completely.

EXAMPLE 18 Bis(iodomethyl)phosphinic acid (1.0 gram) was dissolved in 5% NaOH (9.0 grams). A sample of cotton printcloth was impregnated with the solution, and the fabric was dried at 85 C. and cured for 5 minutes at C., washed, and dried. Fibers from the fabric were insoluindicating crosslinking of the cellulose. The fabric contained 0.37% P, and had a wet wrinkle recovery angle of 253.

We claim:

1. A method of producingbis(chloromethy1)phosphinic acid comprising reacting bis(hydroxymethyl)phosphinic acid with a chlorinating agent selected from the group consisting of SOCl PCI;,, and IPCl and thereafter hydrolyzing the phosphinic chloride thus produced by dissolving it in benzene and adding it dropwise to a vigorously stirred mixture of benzene and Water and thereafter refiuxing.

References Cited UNITED STATES PATENTS 3,110,727 11/1963 Toy et a1. 260502.4

FOREIGN PATENTS 934,090 8/1963 Great Britain 260502.4

OTHER REFERENCES Edmundson et al. J. Chem. Soc., (1966), pp. 1096- 8, Q01C6.

Moedritzer, J. Am. Chem. Soc, (1961), pp. 4381- 4, Q01A5.

BERNARD HELFIN, Primary Examiner I. E. EVANS, Assistant Examiner 

